MUZAFFARABAD, Pakistan, Oct. 15 -- The army was slow to respond, and international aid agencies are in some ways just getting started. But here amid the rubble and the rain at the heart of Pakistan's earthquake zone, the zealous foot soldiers of Jamaat ul-Dawa, one of the country's most prominent Islamic extremist groups, are very much in evidence.

On a sloping muddy field near the rushing Neelum River, the group has established a large field hospital complete with X-ray equipment, dental department, makeshift operating theater, and even a tent for visiting journalists. Dispensaries are piled high with donated stocks of antibiotics, painkillers and other medical supplies.

"Even the army people have come over here to get first aid," said Mohammed Ayub, a long-bearded urologist from Lahore who is volunteering at the field hospital. "The casualties and destruction are so much that they are unable to cope."

Jamaat ul-Dawa is no ordinary charity. Founded in 1989 under a different name, it is the parent organization of Lashkar-i-Taiba, one of the largest and best-trained groups fighting Indian forces in the disputed Himalayan province of Kashmir. Lashkar-i-Taiba has been linked by U.S. authorities to al Qaeda and in 2002 was banned by Pakistan's government as a terrorist organization.

Jamaat ul-Dawa is one of several hard-line Islamic groups that have assumed a prominent role in relief operations following the devastating Oct. 8 earthquake in Pakistani-controlled Kashmir and adjacent areas.

Other groups with a visible presence on Saturday in Muzaffarabad, the largest town in the area, were the charitable wing of Jamiat-i-Islami, an Islamic political party with ideological links to the Palestinian militant group Hamas; and the Al-Rasheed Trust, a Karachi-based charity whose U.S. assets were frozen by the Bush administration in 2003 on grounds that it channeled funds to al Qaeda. The group has denied the charge and says it is focused purely on social welfare.

The groups' effective and visible relief work, analysts say, has bolstered their prestige, possibly at the expense of Gen. Pervez Musharraf, Pakistan's president, and the army, whose initial response was widely criticized as slow and disorganized.

"Definitely they will gain," Ershad Mahmud, an analyst on Kashmir at the Institute for Policy Studies in Islamabad, said of Jamaat ul-Dawa. "They have diverted their whole network toward the relief operation."

Pakistani officials say the army has performed admirably given its own devastating losses in the quake, which killed about 450 soldiers. But in an interview Saturday, Interior Minister Aftab Khan Sherpao acknowledged the vital role of Jamaat ul-Dawa and other such groups, calling them "the lifeline of our rescue and relief work."

Jamaat ul-Dawa, he added, "is only involved in extensive charity work, and their footprint now covers almost the entire quake-affected zone in the country." Pakistan placed Jamaat ul-Dawa on its "terrorism watch list" in late 2003.

The government on Saturday raised its estimate of the death toll from the quake to 38,000, with 62,000 injured. The worst damage was in the part of Kashmir controlled by Pakistan; about 1,400 are thought to have died on the Indian side of the province.

With a chilly rain falling on much of the earthquake zone and early snows dusting nearby mountaintops, aid officials voiced growing concern about the welfare of an estimated 2 million people made homeless by the quake. Already there are signs of disease, with 80 cases of diarrhea reported Saturday in the heavily damaged town of Balakot, up tenfold from the day before. Relief officials estimate that 600,000 toilets will be needed to provide adequate sanitation for survivors.